The present invention relates to a rotary-ring-type log debarker, and more particularly, to a unique ring-type debarker which combines the advantages of both air-seal and air-cell conventional machines, without also exhibiting the disadvantages of either.
Known in the rotary-ring debarking art today are machines which are known as air-seal machines and those which are referred to as air-cell machines. Each offers the user distinct advantages, and each also presents the user with distinct disadvantages.
An air-seal machine is one in which the pressure-fluid path, so-to-speak, between the stator and rotor (ring) in the machine is sealed at the rotary interface between the two with the seal being pressurized under normal debarking operations. Such machines typically carry pressure-fluid cylinders, typically air cylinders, on their respective rotors, which cylinders are drivingly connected for actuation of the debarking tools. An important advantage of an air-seal machine is that debarking contact pressure can easily be changed on the fly simply through adjusting the pressure level of the supplied pressure fluid. In addition, the tools can be shifted to their open conditions also at will on the fly. However, a disadvantage of such machines is that considerable seal wear occurs during normal pressurized operation, and this has dictated an operating practice in the past to limit somewhat the maximum rotary speed of the rotor, thus to extend usable seal life. Naturally, since workpiece throughput is somewhat directly related to rotary ring speed, capping the maximum speed also caps potential additional throughput capacity.
Air-cell machines utilize, typically, inflatable/deflatable air bags (or cells) carried on a rotor, which bags are drivingly connected for actuation of the debarking tools. Air bags, when compared with air cylinders, are considerably lighter, and thus offer reduced-inertia operating advantages over air-cylinder (air-seal) debarkers. In addition, it is typical that air cells are inflated to a desired operating condition through a pressure-fluid supply system that does not include (and does not require) an air-seal interposed a rotor and stator in a machine. As a consequence, air-cell machines can typically be operated at much higher speeds since no seal wear is involved, and accordingly can offer some significant throughput advantages. However, air-cell machines cannot have their operating pressures changed on the fly, nor can their tools be opened on the fly. Rather, an air-cell machine must typically be stopped before an adjustment can be made in cell-operating pressure--an obvious disadvantage.
Proposed according to the present invention is a unique rotary-ring-type log debarker which combines the advantages of both air-seal and air-cell machines, while avoiding the drawbacks of both.
This important objective which is offered by the invention is achieved in a rotary-ring-type debarker which includes an air seal through which pressure fluid is supplied via a pilot-check-like valve to air cells which are drivingly connected to the debarking tools. In this machine, the seal between the rotor and the stator is pressurized only during times that an adjustment is being made in air-cell pressure. During a normal debarking operation, the seal is depressurized, and pressure is maintained in the cells through the check valve mentioned. Accordingly, the proposed new machine is capable of operating at the high rotational speeds offered by conventional air-cell machines. In addition, the proposed machine offers the inertial advantages resulting from reduced weight in the ring-carried air cells.
Operating pressure within the cells can be changed on the fly, and the tools can be opened at will on the fly, simply by repressurizing the rotary seal, and making an appropriate adjustment in pressure-fluid source pressure. The seal in such a machine offers extremely extended useful like inasmuch as it is only subjected to wear during the brief intervals when pressure adjustments are being made in the air cells.
These and other objects and advantages which are attained by the invention will become more fully apparent as the description that now follows is read in conjunction with the accompanying drawings.